Title:
CONSTRUCTION MACHINE
Document Type and Number:
WIPO Patent Application WO/2019/187489
Kind Code:
A1
Abstract:
In the present invention, even when differential pressures before and after direction switching valves associated with respective actuators are extremely low, flow rate control of a hydraulic pump and diversion control of a plurality of direction switching valves can be performed stably, and even when requested flow rates are suddenly changed during transition from a composite operation to a single operation, and the like, the flow rates of pressure oil supplied to the actuators can be prevented from suddenly changing so as to realize excellent composite operability, and meter-in losses of the direction switching valves are reduced to realize high energy efficiency. Requested flow rates of the direction switching valves are calculated from input amounts of operation levers, openings of flow rate control valves are controlled by using the requested flow rates, a meter-in pressure loss of a predetermined direction switching valve is calculated from the requested flow rates of the direction switching valves and meter-in opening areas, and a set pressure of an unload valve is controlled by using the values having been calculated.
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Inventors:
TAKAHASHI KIWAMU (JP)
MAEHARA TAIHEI (JP)
ISHII TAKESHI (JP)
MAEHARA TAIHEI (JP)
ISHII TAKESHI (JP)
Application Number:
PCT/JP2019/000430
Publication Date:
October 03, 2019
Filing Date:
January 10, 2019
Export Citation:
Assignee:
HITACHI CONSTRUCTION MACHINERY TIERRA CO LTD (JP)
International Classes:
F15B11/00; E02F9/22; F15B11/05
Foreign References:
| JPH0742705A | 1995-02-10 | |||
| JP2015105675A | 2015-06-08 | |||
| JP2007505270A | 2007-03-08 | |||
| JP2014098487A | 2014-05-29 |
Other References:
See also references of EP 3660330A4
Attorney, Agent or Firm:
KAICHI IP (JP)
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